All you need to know about Irrawaddy river dolphin
Hyderabad: The Irrawaddy river dolphin (Orcaella brevirostris), not described as a separate species until 2005, were once found throughout the Mekong from the Lao-Cambodia border down the Mekong to the delta in Vietnam and Tonle Sap. The population and range of dolphins have declined greatly in the last 39 years. Less than 300 freshwater Irrawaddy […]
Hyderabad: The Irrawaddy river dolphin (Orcaella brevirostris), not described as a separate species until 2005, were once found throughout the Mekong from the Lao-Cambodia border down the Mekong to the delta in Vietnam and Tonle Sap. The population and range of dolphins have declined greatly in the last 39 years. Less than 300 freshwater Irrawaddy dolphins live in the wild, making these riverine subpopulations critically endangered.
More about them
Featuring a bulging forehead and short beak, this elegant animal will pop its head out of the water to breathe, followed by its back; the tail is rarely seen.
A slate blue to a slate gray colour dolphin, it feeds on bony fish and fish eggs and squirt streams of water that can reach up to 1.5 metre to herd fish into their hunting area.
Irrawaddy dolphins are found in small groups of six or fewer, but up to 25 have been known to gather in deep pools to fish. They are slow swimmers and generally dive when frightened.
Where do they live?
Irrawaddy dolphin populations live in varied habitats including both coastal marine and freshwater tropical environments in Southeast Asia, Indonesia and the Bay of Bengal.
There are five isolated freshwater Irrawaddy dolphin populations: in Myanmar, they live in the Ayeyarwady River (also known as the Irrawaddy River); in Borneo, they live in the Mahakam River; in Cambodia and Lao PDR they live in the Mekong River; in India, they live in Chilika Lake; and in Thailand, they live in Songkhla Lake.
Marine Irrawaddy dolphin populations are found in patches as they prefer to live in sheltered coastal waters where fresh water is flowing in, such as river deltas, mangrove channels, and estuaries. They stick to shallow water and are never found more than a few miles from shore.
Why is it threatened?
Large numbers of this species are killed by entanglement in gill nets and illegal fishing activities including electrofishing. The species is not directly exploited but can accidentally end up in fishing gear.
Habitat degradation and population fragmentation due to dam development have severely impacted the species along with pollution of pesticides from palm oil plantations and mining, mercury poisoning from gold mining hydraulic blasting and dredging.
Conservation status
There is no range-wide estimate for Irrawaddy dolphins, and few populations have been studied rigorously enough to generate population estimates. But where they have been studied, numbers are low (in the 10’s to low 100’s).
An IUCN review concluded that the threats facing the fragmented populations throughout the species range merit a new endangered status on the IUCN Red List 17.
What is WWF doing?
In addition to researching to learn about dolphin mortality, population and ecology, WWF teaches local communities about river dolphins and environmental conservation.
It has developed community fishery management zones to help sustainably manage fish and prevent dolphins from accidental capture in nets and other equipment.
River guards help track the dolphins and enforce sustainable fishing practices to help the population.
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